This invention relates to cigarettes or the like which have been treated with alkali silicates to make them fire resistant. The prior art comprises a number of patents which disclose cigarettes treated with silicates, for example, U.S. Pat. Nos. 1,905,416; 2,049,320; 2,985,175; 3,006,347; 3,030,963; and 3,220,418.
It is known that the pH of cigarette smoke greatly influences its taste. Fire resistant cigarettes of the indicated type when smoked produce a smoke which has an undesirable taste generally involving a harsh bite or a soapy taste.
Simply adding an acid or other additive to the alkali silicate solution of fire resistant cigarettes of the indicated type does not provide a satisfactory solution to the problem. The addition of the acid tends to cause the silicate to precipitate and form a gel by reaction with the SiO.sub.2 of the silicate solution. The resulting gel cannot be satisfactorily applied to the cigarette wrapper.
Accordingly, it would be desirable to provide a free resistant cigarette of the indicated type which produces a smoke that does not have the undesirable taste resulting from the alkalinity of the silicate. It is the general object of this invention to provide such a fire resistant cigarette and a method of making the same.
Briefly stated, the general object of the invention is achieved by the provision of a cigarette or the like which has a flammable wrapper surrounding a body of tobacco, which wrapper has a coating which includes a quantity of an alkali silicate applied as one treatment of the wrapper. In accordance with a preferred embodiment of the invention, a quantity of a pH lowering material is applied as another coating treatment of the wrapper. The dual treatment coating contains quantities of the alkali metal silicate and the acid producing material to make the cigarette fire resistant and to treat the combustion products of the cigarette so as to produce a pleasant smoke. The dual treatment coating in accordance with the invention does not impair the fire resistance imparted to the cigarette by the silicate coating; in fact, the coating of acid producing material, in some instances, may improve the fire resistance of the cigarette.